1/*
2 * This program is free software; you can redistribute it and/or modify it
3 * under the terms of the GNU General Public License version 2 as published by
4 * the Free Software Foundation.
5 *
6 */
7#include <linux/rtc.h>
8#include <linux/time.h>
9
10/**
11 * rtc_set_ntp_time - Save NTP synchronized time to the RTC
12 * @now: Current time of day
13 *
14 * Replacement for the NTP platform function update_persistent_clock64
15 * that stores time for later retrieval by rtc_hctosys.
16 *
17 * Returns 0 on successful RTC update, -ENODEV if a RTC update is not
18 * possible at all, and various other -errno for specific temporary failure
19 * cases.
20 *
21 * If temporary failure is indicated the caller should try again 'soon'
22 */
23int rtc_set_ntp_time(struct timespec64 now)
24{
25	struct rtc_device *rtc;
26	struct rtc_time tm;
27	int err = -ENODEV;
28
29	if (now.tv_nsec < (NSEC_PER_SEC >> 1))
30		rtc_time64_to_tm(now.tv_sec, &tm);
31	else
32		rtc_time64_to_tm(now.tv_sec + 1, &tm);
33
34	rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
35	if (rtc) {
36		/* rtc_hctosys exclusively uses UTC, so we call set_time here,
37		 * not set_mmss. */
38		if (rtc->ops &&
39		    (rtc->ops->set_time ||
40		     rtc->ops->set_mmss64 ||
41		     rtc->ops->set_mmss))
42			err = rtc_set_time(rtc, &tm);
43		rtc_class_close(rtc);
44	}
45
46	return err;
47}
48